Conventional magnetorheological-fluid (MR-fluid) hydraulic mounts include those which are attachable to first and second motor-vehicle components (such as an automobile engine or transmission and an automobile frame) and which have a pumping chamber and a reservoir chamber. The pumping and reservoir chambers are separated by a partition plate having a first through hole containing a decoupler and having a second through hole not containing a decoupler. These mounts also have an electric coil which magnetically influences the second through hole but not the first through hole. Magnetorheological fluid is placed in the pumping and reservoir chambers and in the first and second through holes. The decoupler flexes for relative vibratory motion between the two motor-vehicle components which is of relatively low displacement and higher frequency. The decoupler bottoms out (i.e., reaches its fully flexed limit and flexes no further) for relative motion between the two motor-vehicle components which is of relatively high displacement and lower frequency. Examples of hydraulic-mount decouplers are found in U.S. Pat. Nos. 5,273,262 and 6,622,995.
What is needed is an improved MR-fluid hydraulic mount.